1. Field of the Invention
This invention pertains to a parenteral drug delivery system, and to a drug formulation chamber in combination with a drug delivery device. The invention relates also to a method of parenterally (e.g., intravenously) administering a drug, and to a method of formulating the drug during parenteral administration.
2. Description of the Prior Art
The parenteral administration of medical liquids is an established clinical practice. The liquids are administered particularly intravenously, and the practice is used extensively as an integral part of the daily treatment of medical and surgical patients. The liquids commonly administered include blood and blood substitutes, dextrose solutions, electrolyte solutions and saline. Generally the liquids are administered from an intravenous (IV) delivery system having a container suspended above the patient, with the liquid flowing through a catheter hypodermic needle set to the patient.
The administration of liquids intravenously is a valuable and important practice that contributes to the optimal care of the patient. However, it does not easily provide a satisfactory means and method for administering concomitantly therewith a beneficial agent, such as a drug. In the past, beneficial agents have been administered intravenously by one of the following methods: (1) temporarily removing or disconnecting the IV system administering the agent to the patient, then administering the drug by hypodermic injection (either into the disconnected IV line or directly into the vein of the patient), followed by reinserting the IV system into the patient; (2) adding the agent to the IV liquid in the container which is then carried by the flow of the liquid to the patient; (3) adding the agent to an IV liquid in a secondary container (called a partial fill) that is then connected to the primary IV line; (4) adding the agent to an IV liquid contained in a piggyback vial which is subsequently connected to the primary IV line; or (5) administering intravenously an IV liquid containing a beneficial agent using a pump. While these techniques are used, they have major disadvantages. For example, they often require preformulation of the agent medication by the hospital pharmacist or nurse. They often require separate connections for joining the drug flow line to the primary intravenous line which further complicates intravenous administration. The use of certain types of pumps (e.g., reciprocating pumps) can produce pressures that can vary at the delivery site. Finally, the rate of agent delivery to the patient often is unknown as it is not rate-controlled agent delivery but rather is dependent on the rate of IV fluid flow.
In response to these difficulties, Theeuwes in U.S. Pat. No. 4,511,353 (and in related U.S. Pat. Nos. 4,740,103; 4,740,200 and 4,740,201) developed a formulation chamber adapted to easily fit into a conventional IV administration set. The formulation chamber is adapted to contain a drug delivery device for delivering a drug or other beneficial agent into the IV fluid flowing through the formulation chamber. The drug delivery device within the formulation chamber is selected from osmotic pumps (FIGS. 2a, 2b, 9, 10, and 11), release rate controlling membranes surrounding a drug reservoir (FIGS. 3-5), rate-controlled delivery reservoirs within a pocket in the drug formulation chamber, the pocket formed by a permeable membrane or screen/mesh which allows passage of both IV fluid and drug solution therethrough (FIGS. 12 and 13) and polymer matrices containing the drug, the drug being able to diffuse through the matrix into the flowing IV fluid (FIGS. 6-8). All of these devices provide the advantage of controlling the rate at which the drug or other beneficial agent is released into the IV fluid, independently of the rate at which the IV fluid flows through the formulation chamber. Unfortunately, the drug delivery systems disclosed in these patents do not allow a medical technician to quickly and easily change the type of beneficial agent being delivered into the flowing IV fluid or to quickly and easily change the delivery rate of the beneficial agent so delivered. In order to change the type of agent delivered or the agent delivery rate with the delivery systems disclosed in these patents, it is necessary to completely disassemble the drug formulation chamber and replace the rate-controlled drug delivery device within the chamber. Unfortunately, when the drug formulation chamber is disassembled, there is a break in the sterile field which can lead to patient infection and therefore necessitates re-sterilizing the entire apparatus.
Thus, there remains a need for a drug formulation chamber which can deliver one or more beneficial agents, such as a drug, into an IV fluid flowing in a standard IV administration set and which can quickly and easily change the type and/or change the delivery rate of beneficial agent so delivered without contaminating the sterile field.
Accordingly, it is an object of this invention to provide a parenteral (e.g., intravenous) delivery system which delivers an agent at a controlled rate into a flowing parenteral fluid for optimizing the care of an animal (e.g., a human) whose prognosis benefits from parenteral delivery.
It is another object of the invention to provide an intravenous delivery system having an agent formulation chamber which is adapted to be used with a drug delivery device for admitting a drug or other beneficial agent at a rate controlled by either the drug delivery device, the formulation chamber, or both, instead of by the flow rate of intravenous fluid through the system, for optimizing the care of a patient on intravenous delivery.
Another object of the invention is to provide an intravenous delivery system having an agent formulation chamber which is adapted to be used with a transdermal-type drug delivery device which can deliver one or more beneficial agents, such as a drug, into an IV fluid flowing through the formulation chamber and which can quickly and easily change the type and/or change the delivery rate of beneficial agent so delivered without contaminating the sterile conditions within the drug formulation chamber.
A further object of the invention is to provide an intravenous therapeutic system including a container of an intravenous medical fluid and a drug formulation chamber in combination with a drug delivery device which can deliver drug, to a flowing IV fluid, at a rate which is variable and which is accurately controlled by the components of the system.